Fluid manifold for gas turbine engine and method for delivering fuel to a combustor using same

ABSTRACT

A method for delivering fuel to a combustor of a gas turbine engine includes: injecting fuel into a conduit of a fuel manifold; directing the fuel through a continuous first portion of the conduit; directing the fluid from the first portion into an inflexion of the conduit being a single exit of the first portion; directing the fuel from the inflexion into a second portion of the conduit in serial flow communication with the first portion; and carrying the fuel in the second portion in a direction different from that of the fuel in the first portion. As the fuel flows through the second portion of the conduit, the fuel exits from the second portion of the conduit into a plurality of fuel injection nozzles in exclusive fluid flow communication with the second portion for ejection into a combustor of the gas turbine engine.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 14/135,655 filed Dec. 20, 2013, now U.S. Pat. No. 9,995,220, theentire content of which is incorporated herein by reference.

TECHNICAL FIELD

The application relates generally to gas turbine engines and, moreparticularly, to fuel manifolds for gas turbine engines.

BACKGROUND OF THE ART

Fuel conveying passages, conduits, and manifolds employed internallywithin gas turbine engines and other high-temperature equipment areexposed to high temperatures, particularly those located adjacent thecombustor. Internal fuel manifolds are particularly exposed to hightemperatures given their proximity to the combustor. While the fuelflowing through such internal fuel manifolds provides some cooling, asthe fuel is injected into the combustor, and thus the volume of fuelflowing through the manifold decreases, those portions of the manifoldfurthest away from the fuel inlet are more prone to overheating. Iftemperatures get too high, fuel tends to decompose within these fuelconveying passages causing undesirable accumulations of carbon or coke,which can lead to poor combustor fuel distribution which is detrimentalto the life of the engine.

SUMMARY

In one aspect, there is provided a fuel manifold of gas turbine engine,the manifold comprising: a ring-shaped fuel conveying body; a pluralityof fuel injection nozzles on the body; and at least two fuel conduitsdefined within the body, each of the fuel conduits being fluidlyconnected to a respective separate group of the fuel injection nozzles,each of the fuel conduits extending from a conduit inlet to a conduitend, each of the fuel conduits including: a first portion extendingcontinuously between the conduit inlet and an inflexion of the conduit,the inflexion being a single exit of the first portion such that fuelflows uninterrupted between the conduit inlet and the inflexion; and asecond portion downstream of the first portion and connected thereto inserial flow communication, the second portion extending between theinflexion and the conduit end, the respective separate group of fuelinjection nozzles of the fuel conduit fluidly communicating exclusivelywith the second portion of the fuel conduit.

In another aspect, there is provided a method for delivering fuel to acombustor of a gas turbine engine, the method comprising: injecting fuelinto a conduit of a fuel manifold; directing the fuel through acontinuous first portion of the conduit; directing the fluid from thefirst portion into an inflexion of the conduit being a single exit ofthe first portion; directing the fuel from the inflexion into a secondportion of the conduit in serial flow communication with the firstportion; carrying the fuel in the second portion in a directiondifferent from that of the fuel in the first portion; and as the fuelflows through the second portion of the conduit, exiting the fuel fromthe second portion of the conduit into a plurality of fuel injectionnozzles in exclusive fluid flow communication with the second portionfor ejection into a combustor of the gas turbine engine.

In a further aspect, there is provided a method for delivering fuel to acombustor of a gas turbine engine, the method comprising: injecting fuelinto two conduits of a fuel manifold; for each of the two conduits:directing the fuel through a continuous first portion of the conduit;directing the fluid from the first portion into an inflexion of theconduit being a single exit of the first portion; directing the fuelfrom the inflexion into a second portion of the conduit in serial flowcommunication with the first portion; carrying the fuel in the secondportion in a direction different from that of the fuel in the firstportion; and as the fuel flows through the second portion of each of theconduits, exiting the fuel from the second portion into a plurality ofrespective separate group of fuel injection nozzles in exclusive fluidflow communication with the second portion for ejection into a combustorof the gas turbine engine.

In this specification, the term “inflexion” is defined as an area of afluid conduit defined between two portions of the conduit where the flowin the portion upstream of the inflexion has a direction differentrelative from that of the flow in the portion downstream of theinflexion. Non-limitative examples of inflexions include a local maximumof a conduit, a local minimum of a conduit, a turn of a conduit, or anelbow of a conduit.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures in which:

FIG. 1 is a schematic cross-sectional view of a gas turbine engine;

FIG. 2 is a front perspective view of a fuel manifold for use in a gasturbine engine such as that depicted in FIG. 1;

FIG. 3 is a rear perspective view of the fuel manifold of FIG. 2partially cut-out to reveal conduits of the fuel manifold according to afirst embodiment;

FIG. 4a is a rear elevation view of the fuel manifold partially cut-outof FIG. 3;

FIG. 4b is a schematic of FIG. 4a showing only one internal passage;

FIG. 4c is a schematic view of a cross-section of the internal passagealong line 4 c-4 c of FIG. 4 b;

FIG. 4d is a schematic view of a cross-section of the internal passagealong line 4 d-4 d of FIG. 4 b;

FIG. 5 is a rear perspective view of the fuel manifold of FIG. 2partially cut-out to reveal conduits of the fuel manifold according to asecond embodiment;

FIG. 6a is a rear elevation view of the fuel manifold partially cut-outof FIG. 5;

FIG. 6b is a schematic of FIG. 6a showing only one internal passage; and

FIG. 7 is a flow chart of a method for delivering fuel to a combustor ofthe gas turbine of FIG. 1 using any embodiment the fuel manifold ofFIGS. 2 to 6.

DETAILED DESCRIPTION

FIG. 1 illustrates a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, acompressor section 14 for pressurizing the air, a combustor 16 in whichthe compressed air is mixed with fuel and ignited for generating anannular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases.

Fuel is injected into the combustor 16 of the gas turbine engine 10 by afuel system 20 which includes a fuel source (not shown) and at least onefuel conveying member which is operable to inject fuel into thecombustor 16 for mixing with the compressed air from the compressor 14and ignition of the resultant mixture. The fan 12, compressor 14,combustor 16, and turbine 18 are preferably all concentric about acommon central longitudinal axis 11 of the gas turbine engine 10.

Referring to FIG. 2, the at least one fuel conveying member of the fuelinjection system 20 includes an annular internal fuel manifold 22 havingan inlet 30 which is connected to the fuel source. Fuel enters the fuelmanifold 22 at the fuel inlet 30 and is distributed within the manifold22, in the manner as will be described in further detail below, beforebeing ejected through a plurality of ejection nozzles 26. Although thefuel manifold 22 is shown herein to have a single inlet 30, it iscontemplated that the fuel 22 could have two or more inlets 30.

The fuel manifold 22 is mounted in place adjacent to the combustor 16via suitable mounting elements, which may in one possible embodimentinclude several integral attachment lugs 24. The attachment lugs 24receive pins (not shown) engaged to the support structure. The mountingelements may allow for thermal expansion of the fuel manifold 22 at hightemperatures. It is contemplated that the fuel manifold 22 could bemounted to a support structure surrounding the combustor 16. Forexample, the fuel manifold 22 could be mounted to the engine case. It isalso contemplated that the fuel manifold 22 could be mounted by waysother than the attachment lugs 24. For example, Using fasteners, welds,or the like, which engage the fuel manifold in place to one or more ofthe combustor, the surrounding gas generator casing, etc.

The fuel manifold 22 has a ring-shaped body 23. It is contemplated thatthe fuel manifold 22 could have shapes other than a ring. For example,the fuel manifold 22 could be a half ring or another arcuate shape. Thebody 23 is covered by an outer heat shield which provides the fuelmanifold 22 thermal protection from the high temperature environment ofthe combustor 16. It is contemplated that the outer heat shield could beomitted. The fuel manifold 22 is symmetric with respect to an axis 29.For purposes of orientation, the axis 29 in this specification will bedefined as a vertical axis. The vertical axis 29 defines two portions ofthe fuel manifold 22, namely a right side 17 and a left side 19 ororientation purposes, a bottom 21 of the manifold ring 22 is definedherein to be at a location of the inlet 30 on the fuel manifold 22, anda top 15 is defined herein to be a location of the fuel manifold 22opposite to the inlet 30 along the vertical axis 29, and whichcorresponds to a highest point of the fuel manifold 22. The top 15 andbottom 21 thereby define upward and downward orientations for purposesof orientation in this specification.

The plurality of fuel injection nozzles 26 (fourteen in the embodimentshown in FIG. 2) is provided on a front face 25 of the ring-shaped body23. The fuel injection nozzles 26 atomize the fuel as it is injectedinto the combustor 16 for ignition when mixed with the compressed airtherein. In the depicted embodiment, the injection nozzles 26 aredisposed at equidistance form each other along a circumference 28 of thering-shaped body 23. Nonetheless it is possible to providecircumferentially spaced apart groups of fuel injection nozzles, inwhich case the spacing between fuels nozzles may not be equal throughoutthe circumference 28 of the fuel manifold 22. The fuel injection nozzles26 as described herein may be gas turbine engine fuel injection nozzlesas described, for example, in U.S. Pat. Nos. 7,530,231 and 6,082,113,the entire contents of which are incorporated herein by reference. It iscontemplated that the fuel manifold 22 could have more or less thanfourteen injection nozzles 26. It is also contemplated that theinjection nozzles 26 could span only a portion of the circumference 28of fuel manifold 22.

Turning now to FIG. 3, a rear face 27 of the fuel manifold 22 is showncut off to reveal a first embodiment of conduits (or internal passages)32, 42 of the body 23. The conduits 32, 42 carry fuel from the inlet 30to the injection nozzles 26.

The body 23 includes two concentric conduits 32, 42, the conduit 42being disposed inwardly of the conduit 32. Each of the conduits 32, 42is ring-shaped and runs through almost the entire circumference 28 ofthe fuel manifold 22 (i.e. right side 17 and left side 19). It iscontemplated that one or both of the conduits 32, 42 could run on only aportion of the circumference 28 of the fuel manifold 22. A top 31, 41 ofthe conduits 32, 42 corresponds to the top 15 of the body 23, which isalso a location furthest away from the fuel inlet 30. The tops 31, 41 ofthe conduits 32, 42 are inflexions 34, 44 of the conduits 32, 42. Thismeans that at the tops 31, 41 are local maximums of the conduits 32, 42.

The conduits 32, 42 are fluidly independent from one another, and carryfuel from the inlet 30 each to a different group of injection nozzles26. The conduit 32 distributes fuel to nozzles 26 a on the right side 17of the body 23 exclusively, and the conduit 42 distributes fuel tonozzles 26 b on the left side 19 of the body 23 exclusively. Theconduits 32, 42 being similar to each other, only the conduit 32 willnow be described in further detail.

With reference to FIGS. 4a and 4b , the conduit 32 includes a firstportion 36 (shown solid in FIG. 4b ) disposed on the left side 19 of thebody 23, and a second portion 38 (shown dotted in FIG. 4b ) disposed onthe right side 17 of the body 23 and in fluid flow communication withthe first portion. The first and second portions 36, 38 are connected toeach other by the inflexion 34. The first portion 36 extends arcuately(i.e. it has an arcuate shape) from an inlet end 241 proximal to theinlet 30 up to the inflexion 34, and runs through almost the entire leftside 19 of the body 23. The inlet end 241 is a lowest point of theconduit 32 and is disposed opposite to the inflexion 34 on the verticalaxis 29. It is contemplated that the inlet end 241 and the inflexion 34could not be opposite to each other. For example, the end 241 could beat about 15 degrees from the vertical axis 29. It is also contemplatedthat the inlet end 241 or the inflexion 34 could not be disposed on orabout the vertical axis 29. A cross-section of the first portion 36 ofthe conduit 30 is constant along a length of the first portion 36 fromthe inlet end 241 to the inflexion 34. It is however contemplated thatthe cross-section of the first portion 36 could vary as long as the fuelwould reach the inflexion 34 so as to feed the second portion 38.Although the first portion 36 has a circular cross-section, it iscontemplated that the first portion 36 could have a square, rectangularor oval cross-section.

Fuel travels upwardly in the first portion 36 (indicated by arrow 56)until it reaches the inflexion 34 and the second portion 38. The firstportion 36 is not directly connected to any of the injection nozzles 26a of the right side 17 to which the conduit 32 delivers fuel. Instead,all the fuel entering the first portion 36 exits the first portion 36.Fuel flowing in the first portion 36 of the conduit 32 cools the body 23before it reaches the downstream second portion 38 and the injectionnozzles 26 a. By circulating the fuel through the manifold 22 by priorto injecting any of the fuel provides improved cooling of the manifold22, which, in turn, avoids high wetted wall and fuel temperatures.

The second portion 38 extends between the inflexion 34 and a conduit end45 of the conduit 32, and runs through the entire right side 17 of thebody 23. The fuel traveling in the second portion 38 travels downwardly(as indicated by arrow 60). The inflexion 34 provides a change ofdirection of the flow, and flow in the second portion 38 is in adirection opposite from the flow in the first portion 36. The secondportion 38 is exclusively connected to the injection nozzles 26 a thatare disposed on the right side 17 of the body 23. In the embodimentshown herein, the second portion 38 is connected to seven injectionnozzles 26. Enough fluid has to be provided to the second portion 38 ofthe conduit 32 so that every injection nozzle 26 a on the right side 17is fed with an adequate amount of fuel. The injection nozzles 26 a expelthe fuel to the combustor 16 (arrows 62, only one being referred toavoid cluttering the drawings). The fuel injected in the conduit 32can't access the injection nozzles 26 a of the right side 17 until thefuel has flown through the first portion 36 and changed direction fromupward to downward at the inflexion 34. The fuel injected in the conduit32 does not access any of the injection nozzles 26 b of the left side19, as those are fed by the conduit 42 exclusively.

In order to ensure that the fuel reaches each of the fuel injectionnozzles 36 at a desired velocity, a cross-section flow area of thesecond portion 38 of the conduit 32 may decrease along a length of thesecond portion 38 from the inflexion 34 to the conduit end 45, as can beseen in FIGS. 4b, 4c and 4d . This decrease in cross-section flow areaof the second portion 38, which may be continuous and gradual, isdesigned to maintain the velocity of the fuel substantially constantthrough the second portion 38. In the embodiment shown in FIG. 4a , thecross-section flow area at location 70 of the second portion 38 islarger than the cross-section flow area at location 72 of the secondportion 38. In the embodiment shown, the location 70 is upstream of thelocation 72 along the length of the second portion 38 from the inflexion34 to the conduit end 45. It is however contemplated that thecross-section of the second portion 38 of the conduit 32 could vary in amanner different from described above or could not vary at all, as longas the fuel reaches the conduit end 45. Although the second portion 38has a circular cross-section, it is contemplated that the second portion38 should be square, rectangular or oval in cross-section. The first andsecond portions 36, 38 could have different cross-sections (shapes anddimensions).

Fluid in the conduit 32 travels counter-clockwise when the fuel manifold22 is seen from the rear face 27 as shown in FIG. 4a . Fluid in theconduit 42 travels in opposite direction from the fluid in the conduit32, i.e. counter-clockwise when the fuel manifold 22 is seen from therear face 27 as shown in FIG. 4 a.

Turning now to FIG. 5, the rear face 27 of the fuel manifold 22 is showncut out to reveal a second embodiment of conduits (or internal passages)132, 142 of the body 23. The conduits 132, 142 are symmetric withrespect to each other relative to the vertical axis 29. The left side 19receives the conduit 132 only, and the right side 17 receives theconduit 142 only. In this embodiment, the conduits 132, 142 arerestricted to one portion of the circumference 28.

Each of the conduits 132, 142 has an arcuate shape, with a respectiveinflexion 134, 144 disposed at the top 15 of the body 23. The inflexions34, 44 are elbows (or U-turns), redirecting the flow of fuel at 180degrees. The inflexions 34, 44 are disposed at a highest point of eachof the conduits 132, 142, which is also a point furthest away from thefuel inlet 30. It is contemplated that the inflexions 134, 144 could bedisposed away from the vertical axis 29 and/or that the inflexions 134,144 could be located at a location in the fuel manifold 22 between thetop 15 and the bottom 21 of the body 23. For example they could be at amid-height of the fuel manifold 22.

The conduits 132, 142 are fluidly independent from one another, andcarry fuel from the inlet 30 to the injection nozzles 26 b on the left19, and the injection nozzles 26 a on the right 17 side of the body 23,respectively. The conduits 132, 142 being similar, only the conduit 132will now be described in further detail.

With reference to FIGS. 6a and 6b , the conduit 132 includes a firstportion 136 (shown solid in FIG. 6b ) and a second portion 138 (showndotted in FIG. 6b ). The first and second portions 136, 138 are fluidlyconnected to each other at the inflexion 134. The first portion 136 isdisposed radially outwardly relative to the second position 138, andboth lie in a common plane that is perpendicular to the centrallongitudinal axis 11 of the engine 10. It is contemplated, however, thatthe first portion 136 could be disposed inwardly relative to the secondposition 138. It is also contemplated that the first portion 136 andsecond portions 138 could cross (without fluidly connecting) each other.The first portion 136 could for example have a substantially zigzagshape, thus extending on each side of the second portion 138. The firstand second portions 136, 138 could also be in a same plane perpendicularto the front 25 and rear faces 27 of the fuel manifold 22.

The first portion 136 extends from an inlet end 141 proximal to theinlet 30 up to the inflexion 134. As such, the first portion 136 runsthrough the entire left side 19 of the body 23. The end 141 is a lowestpoint of the conduit 132 and is disposed about opposite to the inflexion134 on the vertical axis 29. It is contemplated that the inlet end 141could not be opposite to the inflexion 134. For example, the inlet end141 could be at about 15 degrees from the vertical 29. Fuel travelsupwardly in the first portion 136 (indicated by arrow 156) until itreaches the inflexion 134. Fuel exits the first portion 136 of theconduit 132 only at the inflexion 134. The first portion 136 is notdirectly connected to any of the injection nozzles 26 b of the left side19. All the fuel entering the first portion 136 exits the first portion136. As such, the first portion 136 is continuous and has only a singleexit, namely the inflexion 134. Fuel flowing in the first portion 136 ofthe conduit 132 cools the body 23 of the fuel manifold 22 beforereaching the downstream second portion 138 and the injection nozzles 26b. Cooling of the fuel manifold 22, avoids high wetted wall and fueltemperatures. The cross-section of the first portion 136 of the conduit132 is constant along the length of the first portion 136 from the inletend 141 to the inflexion 134. It is however contemplated that thecross-section of the first portion 136 could vary as long as the fuelreaches the inflexion 134 and feeds the second portion 138.

The second portion 138 extends between the inflexion 134 and a conduitend 145 of the conduit 132. The fuel traveling in the second portion 138travels downwardly (as indicated by arrow 160). Because of the 180degree elbow shape of the inflexion 134, flow in the second portion 138is in opposite direction from the flow in the first portion 136. Thesecond portion 138 is connected the injection nozzles 26 b of the leftside 19 of the body 23 exclusively. In the embodiment shown herein, thesecond portion 138 is connected to seven injection nozzles 26 b. Enoughfluid has to be provided to the second portion 138 of the conduit 132 sothat every injection nozzle 26 b on the left side 19 is feed with anadequate amount of fuel. The injection nozzles 26 b expel the fuel tothe combustor 16 (arrows 162, only one being referred to avoidcluttering the drawings). The fuel injected in the conduit 132 can'taccess the injection nozzles 26 b of the left side 19 until the fuel hasflown through the first portion 136 and turned at the inflexion 134. Thefuel injected in the conduit 132 whether the first portion 135 or thesecond portion 138 does not access any of the injection nozzles 26 a ofthe right side 17, as this is achieved by the conduit 142 exclusively.

In order to ensure that the fuel reaches each of the fuel injectionnozzles 26 b at a desired velocity, the cross-section of the secondportion 138 of the conduit 132 may decrease along the length of thesecond portion 138 from the inflexion 134 to the conduit end 145. Thisdecrease in cross-section of the second portion 138, which may becontinuous and gradual, is designed to maintain the velocity of the fuelsubstantially constant through the second portion 138. It is howevercontemplated that the cross-section of the second portion 138 of theconduit of the fuel manifold 22 could vary in a manner different fromdescribed above or could not vary at all, as long as the fuel reachesthe conduit end 145.

With reference to FIG. 7, a method 60 for delivering fuel to thecombustor 16 using the manifold 22 will now be described. The method 60will be shown applied to the conduit 32 as one example of configurationwhere it could be applied. Flows though the conduits 42, 132, 142 aresimilar to the one through the conduit 32, and could be used with themethod 60.

The method 60 starts at step 62 with injecting fuel to the conduit 32 ofthe fuel manifold 22. Fuel is introduced via the inlet 30, as indicatedby arrow 52 and is diverted into the inlet end 241 of the first portion36 (arrow 54). At step 64, fuel is directed through the first portion 36of the conduit 32, thereby at least partially cooling the fuel manifold22. Fuel travels upwardly through the first portion 36 as indicated byarrow 56, until it reaches the inflexion 34. At step 66, fuel isdirected through the inflexion 34 where it undergoes a change ofdirection from upwards to downwards. Because the first portion 36 of theconduit 32 is continuous and has a single exit at the inflexion 34, allof a given volume of fuel that is introduced into the first portion 36exits the first portion 36 (i.e. flow through the first portion 36 isuninterrupted and none is diverted off for feeding fuel injectors orotherwise). Accordingly, fuel is permitted to flow through a portion ofthe fuel manifold 22, in this case approximately half of the diameter ofthe manifold ring 22, before being fed to some of the nozzles 26, inthis case the nozzles 26 a for injection. At the inflexion 34 the fuelchanges direction (in the case of the conduits shown herein it reversesdirection) and enters the second portion 38. At step 68, the fuel isdirected through the second portion 38 of the conduit 32. In the secondportion 38, the fuel now travels downwardly (arrow 60) with the help ofgravity. At step 69, the fuel exits at those ejecting nozzles 26 a onthe right side 17 while traveling in the second portion 38 of theconduit 32. Fuel feeds the injection nozzles 26 a as it encounters themduring its travel toward the conduit end 45.

With the configuration described above, no additional coolant isnecessary (although coolant may be added to the fuel manifold 22). Thefuel itself is cooled down before being circulated back into the fuelmanifold 22 to feed the injection nozzles 26. This may ensure moreconsistent cooling of the fuel and of the manifold 22.

It should be understood that for a given embodiment, the conduits 32, 42(resp. 132, 142) may be operated simultaneously or in a sequentialmanner, depending on the needs of the engine 10.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention disclosed.For example, the fuel manifold may have only one conduit to feed all theinjection nozzles. The conduit may be ring shaped and the inflexion maybe the lowest point of the conduit and may be located adjacent to thefuel inlet. In another example, there may be more than two conduits, forexample three, thereby feeding each one of three groups of injectionnozzles. Although the present is described for an internal fluidmanifold, it is contemplated that the conduits described herein could beapplied to an external manifold. Still other modifications which fallwithin the scope of the present invention will be apparent to thoseskilled in the art, in light of a review of this disclosure, and suchmodifications are intended to fall within the appended claims.

The invention claimed is:
 1. A method for delivering fuel to a combustorof a gas turbine engine, the method comprising: injecting fuel into aconduit of a fuel manifold via a conduit inlet, the fuel manifold havinga ring-shaped body; directing the fuel through a continuous firstportion of the conduit extending between the conduit inlet and aninflexion of the conduit, the first portion of the conduit disposed in afirst half of the ring-shaped body; directing the fluid through theinflexion of the conduit, the inflexion forming a single exit of thefirst portion and being U-shaped, the inflexion located opposite fromthe conduit inlet relative to the ring-shaped body; directing the fuelthrough a second portion of the conduit in serial flow communicationwith the first portion, the second portion of the conduit extendingdownstream from the inflexion, wherein fuel flowing in the secondportion flows in a direction opposite to that of the fuel flowing in thefirst portion, the second portion of the conduit disposed in said firsthalf of the ring-shaped body; and as the fuel flows through the secondportion of the conduit, exiting the fuel from the second portion of theconduit into a first group of fuel injection nozzles in exclusive fluidflow communication with the second portion for ejection into thecombustor of the gas turbine engine.
 2. The method as defined in claim1, further comprising at least partially cooling the fuel manifold as aresult of directing the fuel through the first portion of the conduit.3. The method as defined in claim 1, further comprising flowing the fuelat a constant velocity as the fuel flows through the second portion ofthe conduit.
 4. The method as defined in claim 1, further comprising:injecting fuel into a second conduit of the fuel manifold via theconduit inlet; directing the fuel through a continuous first portion ofthe second conduit extending between the conduit inlet and an inflexionof the second conduit, the first portion of the second conduit disposedin a second half of the ring-shaped body of the fuel manifold; directingthe fluid through the inflexion of the second conduit, the inflexion ofthe second conduit forming a single exit of the first portion of thesecond conduit and being U-shaped, the inflexion of the second conduitlocated opposite from the conduit inlet relative to the ring-shapedbody; directing the fuel through a second portion of the second conduitin serial flow communication with the first portion of the secondconduit, the second portion of the second conduit extending downstreamfrom the inflexion of the second conduit, wherein fuel flowing in thesecond portion of the second conduit flows in a direction opposite tothat of the fuel flowing in the first portion of the second conduit, thesecond portion of the second conduit disposed in said second half of thering-shaped body; and as the fuel flows through the second portion ofthe second conduit, exiting the fuel from the second portion of thesecond conduit into a second group of fuel injection nozzles inexclusive fluid flow communication with the second portion of the secondconduit for ejection into the combustor of the gas turbine engine.